Thermal expansion feature for an exhaust gas cooler

ABSTRACT

An exhaust gas cooler and a method of manufacturing an exhaust gas cooler comprising providing a shell, disposing within the shell a tube bundle/core through which exhaust gas passes, and situating a seal or gasket assembly providing a liquid-tight seal between the shell and the tube bundle/core and between each tube of the tube/bundle core.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not Applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

INCORPORATION BY REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC

Not Applicable.

COPYRIGHTED MATERIAL

Not Applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention (Technical Field)

The present invention relates to exhaust gas coolers and methods ofmaking and using same.

2. Description of Related Art

In some engine applications the high temperature of the exhaust gas thatenters an exhaust gas cooler combined with the cyclic nature of the gasflow creates a thermal stress within the cooler core. This will lead tofatigue failure depending on the temperature and number of cycles. A wayto reduce the stress in the core is required in order to prolong thedurability of the cooler.

One attempt for handling this issue is disclosed in U.S. Pat. No.7,044,116, entitled “Exhaust heat exchanger in particular for motorvehicles”, relating to an exhaust cooler for motor vehicles with exhaustrecycling. A sliding seating is arranged in the force flow, either inthe housing sleeve or between a tube plate and the housing sleeve. Thesliding fit is between two components which can slide in relation to oneanother, in what is referred to as a loose bearing, in contrast to afixed bearing. Such a sliding fit compensates for the different degreesof expansion of the nest of pipes and housing, i.e., the abovementionedstresses are diminished.

The present invention provides a solution that is much less complicatedand does not require the sliding arrangement of the prior art, as wellas providing additional benefits, namely an intermediate seal or gasketbetween the header plate and the individual tubes of the exhaust gascooler. While other heat exchangers are known to have a gasket betweenthe tubes and header to form a seal, the gasket on these units is toallow a unit to be assembled without brazing. Like gaskets are used atboth ends of the tubes. The present invention is still brazed, but theseal allows for thermal expansion of the non-brazed tube ends. Thecooled medium of the invention is exhaust gas through the tubes cooledby coolant over the tubes.

BRIEF SUMMARY OF THE INVENTION

The present invention is of an exhaust gas cooler and a method ofmanufacturing an exhaust gas cooler, comprising: providing a shell;disposing within the shell a tube bundle/core through which exhaust gaspasses; and situating a seal or gasket assembly providing a liquid-tightseal between the shell and the tube bundle/core and between each tube ofthe tube/bundle core. In the preferred embodiment, the seal or gasketassembly is situated proximate an end of the tube bundle/core, mostpreferably proximate the cold end of the tube bundle/core. The seal orgasket assembly preferably comprises a seal or gasket comprising one ormore of rubber, silicone, and a polymer, and the assembly preferablycomprises a header between the shell and the seal or gasket. The seal orgasket preferably comprises a notch accepting the header and has arounded interior profile. The tube bundle/core preferably comprisestubes with unbrazed ends. The tubes are preferably flared and have finsrecessed to accommodate the flared ends.

Objects, advantages and novel features, and further scope ofapplicability of the present invention will be set forth in part in thedetailed description to follow, taken in conjunction with theaccompanying drawings, and in part will become apparent to those skilledin the art upon examination of the following, or may be learned bypractice of the invention. The objects and advantages of the inventionmay be realized and attained by means of the instrumentalities andcombinations particularly pointed out in the appended claims.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The accompanying drawings, which are incorporated into and form a partof the specification, illustrate one or more embodiments of the presentinvention and, together with the description, serve to explain theprinciples of the invention. The drawings are only for the purpose ofillustrating one or more preferred embodiments of the invention and arenot to be construed as limiting the invention. In the drawings:

FIG. 1 is a front perspective view of an exhaust gas cooler according tothe invention; and

FIG. 2 is a front perspective detail of the invention shown in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

The present invention allows the tubes of an exhaust gas cooler toexpand and contract without restraining them within the core bundle.This is achieved by the use of an intermediate seal or gasket betweenthe header plate and the individual tubes. The seal prevents coolantfrom leaking out of the cooler and lets the tube length increase anddecrease with the variation of the exhaust gas temperature. The seal isapplied to the cold end of the core, where the temperatures are lowenough on the tube wall to allow a polymer to be used withoutdegradation over time. The geometry of the arrangement also encouragescorrosive condensate to run away from the seal.

The cooler core is preferably brazed before assembly of the gasket sealonto the tubes. The gasket is preferably pushed over the tube ends andthrough the header. After assembling the gasket onto the tubes andheader plate the tube ends are preferably expanded (flared) to resistthe tendency of the pressurized coolant to force the gasket off the endsof the tubes. In a cooler with a secondary surface within the tubes thefin are preferably recessed within the tube to allow passage for theexpansion punch.

Referring to the Figures, the exhaust gas cooler 10 of the inventioncomprises shell 12, tube bundle/core 14, and seal or gasket 16. The sealpreferably comprises rubber, silicone, or polymer able to withstand thetemperature ranges expected to be encountered by the particular exhaustgas cooler at issue. Inset 18 of FIG. 1 is shown in detail in FIG. 2.Header 20 is placed within the shell and fits into a corresponding notchin the seal or gasket, forming a seal or gasket assembly. If fins 24 areemployed within one or more tubes of the tube bundle/core, then the finsare preferably recessed to allow for flaring 22 of the tubes at the endswith the seal or gasket. The seal or gasket preferably has a roundedprofile on its interior, as shown in FIG. 2, to ease insertion onto thetube bundle/core.

Although the invention has been described in detail with particularreference to these preferred embodiments, other embodiments can achievethe same results. Variations and modifications of the present inventionwill be obvious to those skilled in the art and it is intended to coverin the appended claims all such modifications and equivalents. Theentire disclosures of all references, applications, patents, andpublications cited above are hereby incorporated by reference.

1. An exhaust gas cooler comprising: a shell; a tube bundle/core throughwhich exhaust gas passes; and a seal or gasket assembly providing aliquid-tight seal between said shell and said tube bundle/core andbetween each tube of said tube/bundle core.
 2. The exhaust gas cooler ofclaim 1 wherein said seal or gasket assembly is located proximate an endof said tube bundle/core.
 3. The exhaust gas cooler of claim 2 whereinsaid seal or gasket assembly is located proximate the cold end of saidtube bundle/core.
 4. The exhaust gas cooler of claim 1 wherein said sealor gasket assembly comprises a seal or gasket comprising one or more ofthe group consisting of rubber, silicone, and a polymer.
 5. The exhaustgas cooler of claim 4 wherein said seal or gasket assembly comprises aheader between said shell and said seal or gasket.
 6. The exhaust gascooler of claim 5 wherein said seal or gasket comprises a notchaccepting said header.
 7. The exhaust gas cooler of claim 4 wherein saidseal or gasket comprises a rounded interior profile.
 8. The exhaust gascooler of claim 1 wherein said tube bundle/core comprises tubes withunbrazed ends.
 9. The exhaust gas cooler of claim 1 wherein said tubebundle/core comprises tubes with flared ends.
 10. The exhaust gas coolerof claim 9 wherein said tube bundle/core comprises one or more tubeswith fins recessed to accommodate said flared ends.
 11. A method ofmanufacturing an exhaust gas cooler, the method comprising the steps of:providing a shell; disposing within the shell a tube bundle/core throughwhich exhaust gas passes; and situating a seal or gasket assemblyproviding a liquid-tight seal between the shell and the tube bundle/coreand between each tube of the tube/bundle core.
 12. The method of claim11 wherein in the situating step the seal or gasket assembly is situatedproximate an end of the tube bundle/core.
 13. The method of claim 12wherein in the situating step the seal or gasket assembly is situatedproximate the cold end of the tube bundle/core.
 14. The method of claim11 wherein in the situating step the seal or gasket assembly comprises aseal or gasket comprising one or more of the group consisting of rubber,silicone, and a polymer.
 15. The method of claim 14 wherein in thesituating step the seal or gasket assembly comprises a header betweenthe shell and the seal or gasket.
 16. The method of claim 15 wherein inthe situating step the seal or gasket comprises a notch accepting theheader.
 17. The method of claim 14 wherein in the situating step theseal or gasket comprises a rounded interior profile.
 18. The method ofclaim 11 wherein in the disposing step the tube bundle/core comprisestubes with unbrazed ends.
 19. The method of claim 11 wherein in thedisposing step the tube bundle/core comprises tubes with flared ends.20. The method of claim 19 wherein in the disposing step the tubebundle/core comprises one or more tubes with fins recessed toaccommodate the flared ends.